Is 'The Pulsar Positioning System' Evidence For SETI?

Clément Vidal, author of a new paper about astrophysics and the search for extraterrestrial intelligence, poses an interesting question about pulsars:

To emphasize the significance of this research program, imagine that we would find around Mars’ orbit well-distributed timekeeping devices with a precision comparable to atomic clocks, beaming timing information that can be used as a “Mars Positioning System”, just like GPS. Wouldn’t we be compelled to explore the hypothesis that extraterrestrial intelligence is at play? This is exactly the current situation with millisecond pulsars, but on a galactic scale.

In the view of the author, pulsars could not only be used as a navigation system but are also sufficiently good clocks that they could be used to synchronize the work of a civilization.

First, all pulsars could be perfectly natural, but we can reasonably expect that civilizations in the galaxy will use them as standards (section 6). By studying and using XNAV, we are also getting potentially ready to receive and send messages to extraterrestrial intelligence in a galactically meaningful way. From now on, we might be able to decipher a first level of timing and positioning metadata in any galactic communication. We made a first risk-benefit analysis of asking permission to use PPS, but this largely remains to be debated.

Second, what remains uncertain is whether the pulsar positioning system is natural or artificial. We put forward the SETI-XNAV quest to answer this issue. It draws on pulsar astronomy, and navigation and positioning science to make SETI predictions. This concrete project is grounded in a universal problem and need: navigation. Decades of pulsar empirical data is available, and I have proposed 9 lines of inquiry to start the endeavor (section 5). These include predictions regarding the spatial and power distribution of pulsars in the galaxy, their population, their evolutionary tracks, possible synchronization between pulsars, testing the navigability near the speed of light, decoding galactic coordinates, testing various directed panspermia hypotheses, as well as decoding metadata or more information in pulsar’s pulses.

As far as I know, the earliest reference to this idea is in George O. Smith's 1952 story Troubled Star; he described a space beacon.

In his paper, Vidal states that by observing three or more pulsars, a position can be determined.

In his 1959 short story The Repairman, Harry Harrison wrote about automated hyperspace beacons placed at ideal locations on lonely planets, as well as the number of beacons needed to determine one's position in the galaxy:

The first ships to enter hyperspace had no place to go - and no way to tell if they had even moved. The beacons solved that problem and opened up the entire universe. They are built on planets and generate tremendous amounts of power...

For a hyperspace jump, you need at least four beacons for an accurate fix. For long jumps, navigators use up to seven or eight. So every beacon is important and every one has to keep operating...
(Read more about Harry Harrison's hyperspace beacons)